No, you can't book the package online. What you have is a regular restaurant reservation, which will not get you Fantasmic seating.
If you want the package you will need to call 407-WDW-DINE and specifically ask for the Fantasmic package. You will need to give a credit card number to guarantee the reservation for the package, it'll be charged a no-show fee if you don't cancel and don't show up.
Just called yesterday when our window opened up and booked Fantasmic Lunch package at Mama Melrose. You have to book it online and you can use the DDP for 1 TS. Price for lunch at MM was around 35 per adult and 12 per child.
Are you saying you can now book the Fantasmic package on line, or is this an error since you say you called and booked? Would be wonderful if it was all on line now...
I called and got Fantasmic package for Dec. 11 this morning, gave credit card info...all set. I'm glad I knew the schedule because the CM told me it doesn't run on Saturdays and when I told him the schedule said it's on, he then checked and said - "that's correct!" A person who didn't know would have missed out...